1. Field of the Inventions
The present invention generally relates to applying an aggregate to an expandable tubular. More particularly, the present invention describes a method of applying aggregates on a flexible material to an expandable tubular.
2. Background of the Invention
In recent years, the use of expandable tubulars has become more common in the drilling and completion phases of well bore construction. Bits/aggregates are glued to the outside diameter of expandable tubular to act as anchors when expanded. For example, the bits/aggregates hold a liner in place. The liner/tubing is run down hole in the casing to the desired location and the liner/tubing is expanded until it seats against the casing. The high pressure of the expansion imbeds the bits/aggregates in both the liner and casing, which holds the liner in place.
In order for such anchoring devices to function properly, the entire circumference of the tubing in a specified length needs to be covered by bits/aggregates (as illustrated in FIG. 1). Such a length may vary, for example, from 3 to 12 inches. The bits/aggregates are generally small and are glued to the tubing/tubular. The size of the bits/aggregates may range from 0.062 to 0.250 inch. The bits/aggregates can have shapes as needed/specified. The glue can only use 50% of the height of the bit/aggregate for adhering it to the tubing. The glue typically begins to set in half an hour. The glue cannot sag or have runs and must be smooth over the surface of the tubing. A specified thickness must be consistent over the entire circumference of the tubing. It is also important to meet the requirement of bit/aggregate count per square inch, which is determined by the size of the bit. For example, a bit size of 0.062 to 0.125 inch could have a bit count of 25 to 36 pieces per square inch.
The glue and bits/aggregates must be applied on top of the tubing at a specific location. If the tubing is rolled, the bits/aggregates will fall off, or sag away and lose their spacing. Currently, the bits/aggregates must be applied one at a time. The bits/aggregates cannot touch each other. Applying the bits/aggregates is an arduous and time-consuming process that demands skill and experience. If the glue starts to cure, the bits/aggregates will not adhere. The aggregates/bits can be applied to only a small area of the tubular at one time. After the application of the bits/aggregates, the glue must be allowed to cure. For example, eight to ten hours is enough for the bits/aggregates to adhere and remain in place. Care must be taken not to touch the bits for 24 to 36 hours until the glue is fully cured. Then the next section of the tubular can be applied. This process is repeated until the entire circumference and required length is covered.
For example, on a tubing with four-inch outer diameter (OD), a one-inch area of the circumference and 12 inch long can be applied in one application. With bits being 0.125 inch long, 420 bits are needed for this area. Approximately 5040 bits are required for the entire application in this example.
Accordingly, there is continuing need and interest to develop methods and systems to apply aggregates to expandable tubulars.